Polycrystalline diamond compact (PDC) cutters and diamond enhanced inserts (DEIs) have been used in industrial applications including rock drilling and metal machining for many years. Generally, a compact or layer of polycrystalline diamond (PCD) (or other superhard material) is bonded to a substrate material, such as a sintered metal-carbide, e.g., cemented tungsten carbide, to form a cutting structure. PCD generally includes a polycrystalline mass of diamonds that are bonded together to form an integral, tough, high-strength mass or lattice. The resulting PCD structure has enhanced wear resistance and hardness, making PCD materials useful in wear and cutting applications where high levels of wear resistance and hardness are desired.
A PDC cutter or DEI may be formed by placing a cemented carbide substrate into the container of a press. A mixture of diamond particles or diamond powder is placed atop the substrate and treated under high-pressure high-temperature (HPHT) conditions. In doing so, metal binder (often cobalt) migrates from the substrate and passes through the diamond grains to promote intergrowth between the diamond grains. As a result, the diamond grains become bonded to each other to form the diamond layer, and the diamond layer is in turn bonded to the substrate. The substrate often includes a metal-carbide composite material, such as tungsten carbide. The deposited diamond layer is often referred to as the “diamond table” or “abrasive layer.” The term “particle” refers to the powder employed prior to sintering a superabrasive material, while the term “grain” refers to discernable superabrasive regions subsequent to sintering.
Generally, PCD may include any suitable amount of diamond and binder, e.g., from 85 to 95% by volume diamond and a balance of the binder material, the binder being present within the interstices existing between the bonded diamond grains. Binder materials used for forming conventional PCD include metals from Group VIII of the Periodic Table, such as cobalt, iron, or nickel and/or mixtures or alloys thereof. Higher metal content increases the toughness of the resulting PCD material, but may also decrease the PCD material hardness, thus making it difficult to improve both hardness and toughness. Similarly, when variables are selected to increase the hardness of the PCD material, brittleness may also increase, thereby reducing the toughness of the PCD material.